This invention relates to a method of and a structure for improving light efficiency through a double heterojunction in AlGaAs red light emitting diodes (LED's) by reducing contact shadowing due to current crowding beneath the contact area. These AlGaAs LED's are for use in, for example, optical fiber communication systems.
Presently, AlGaAs light emitting diodes which are characterized by a double heterojunction have low luminous efficiencies because of contact shadowing due to current crowding at the p-n junction of the diode under the contact area. As external contact is made to the structure through a metal contact attached to the heterojunction region, light is emitted along the p-active layer as holes from the p-active layer (p-region) and electrons injected from the n-region of the p-n junction recombine to produce photons. However, the light emitted along the p-n junction under the contact is absorbed by the contact, which in effect acts as a shadow to a portion of the light being emitted from the entire p-n junction, thus reducing the total external light output. Therefore, in order to increase the output of the light being emitted along the entire p-n junction of the diode it is essential to minimize contact shadowing beneath the contact area.